Replacement IIe PSU?

[Newsdee]

So I have two IIe, one I had as a kid and a second spare I got from college when they were throwing old stuff away.

 

Today I decided to try the spare after having it for many years in storage, but long story short it only ran for a few minutes until I heard a pop and a bit of "magic smoke" came out of the PSU.

Immediately switched it off, but now I need to figure out if it's repairable or whether to get a replacement.

 

I'm also wondering if it's safe to try my main machine as well. I've never used it in the country I'm in now so don't want to ruin it.

Both units have a PSU rated for 220V at 50hz which match the mains power in my region, so I don't think that caused the failure.

 

Looking on e-bay there's a guy selling a cable with the motherboard connector, so perhaps I could use a mini AT power supply as replacement.

Edited April 3, 2016 by Newsdee

[Newsdee]

Opening up the PSU, the capacitors seem OK but the 0.1uF resistor(?) is destroyed (bloated and parts chipped off). Could it be a short, or are those part also prone to failure?

 

Edit: It's one of the RIFA filter caps described in this page: http://obsolescenceguaranteed.blogspot.hk/2014/03/bad-caps-or-recap-kids-apple-iie-power.html

Edited April 3, 2016 by Newsdee

[trash_44fr]

Hello Newsdee,

 

You can safely remove the RIFA cap and clean the PSU. It will work without it.

If you get replacement, be sure to buy a X cap (or X2, depending of your type of PSU).

Edited April 3, 2016 by trash_44fr

[Newsdee]

Tried removing it but it doesn't seem to work. I guess there must be other components affected

[Newsdee]

Update: actually the fuse had blown, now the PSU is working on the spare IIe. I'll do some diagnostics before trying my CFFA3000 on it.

 

My main IIe doesn't even beep on boot though. Its PSU is harder to open so I'll try to get it repaired by a local electrician first. It has socketed chips so I guess some might need reseating, although I hope it's not something more complex than that or it'll be tricky to debug...

[Newsdee]

So now I have one working PSU, one booting spare machine with wonky video, and my main machine doesn't boot (no beep).

 

I resocketed all chips and even tried swapping chips betweem boards (at least those that are socketed in the spare MB), but I still get no beep. I removed all expansion cards, and even tried booting without the RAM chips (in case one was wrong). Nothing.

 

At some point I got some garbage characters out but after reseating more chips that went away and it went back to having no video whatsoever.

 

I guess I need to track donr an old service manual and try replacing the chips they recommend...

[trash_44fr]

You're out of luck since unlike the II and II+, the //e is using proprietary chips like the MMU and the IOU.

I was able to repair a //e motherboard one time but it was a real pain : I have to unsolder every IC, put them into sockets and try them one by one to see if they were good on another working motherboard.

Unless you have time and knowledge and passion, it is better to buy a working motherboard.

Edited April 10, 2016 by trash_44fr

[Newsdee]

You're out of luck since unlike the II and II+, the //e is using proprietary chips like the MMU and the IOU.

I was able to repair a //e motherboard one time but it was a real pain : I have to unsolder every IC, put them into sockets and try them one by one to see if they were good on another working motherboard.

Unless you have time and knowledge and passion, it is better to buy a working motherboard.

I'm lucky that my (main) motherboard has sockets for all ICs already. I suppose I could order those chips that aren't removable from my spare board and hope for the best.

 

I could get video out sometimes with rows of random characters, so it seems video circuitry is OK at least.